I believe there might be a confusion in the terminology. As of my last knowledge update in September 2021, there is no well-known control method called "pole amplitude modulation" for controlling induction motor speed. Induction motors are typically controlled using techniques like voltage/frequency control, scalar control, and vector control.
However, I can explain the concept of "Pole Amplitude Modulation" as it might relate to some other context or technology that emerged after my last update. If this is a new concept, I might not have information about it.
In a general context, amplitude modulation (AM) involves varying the amplitude of a carrier signal in accordance with the amplitude of a modulating signal. This technique is commonly used in radio communications. If you replace "carrier signal" with "pole configuration" and "modulating signal" with some control signal, you might be referring to a method where the pole configuration (number of poles) of the motor is modulated to control its speed.
The concept of varying the pole configuration of an induction motor is not commonly used for speed control because changing the number of poles in an induction motor usually involves physically altering the motor's structure. This is a complex process and isn't a practical method for real-time speed control. Instead, motor control is typically achieved by adjusting voltage, frequency, or both using methods like variable frequency drives (VFDs) for precise speed control.
If "pole amplitude modulation" is indeed a new concept or terminology that has emerged after September 2021, I recommend referring to up-to-date technical literature, research papers, or official sources for accurate information on this topic.